Hello,
My issue is regarding the identification of the elastic properties of a composite material, starting from the data obtained from tensile tests. Unfortunately, I have found your tool only now, as I have already developed a script which launches abaqus iteratively, and then computes a square-root error index between the numerical and the experimental results of 11 specimens, each one with fibers oriented in a different way. The variables are the elastic properties of the material, so E11, E22, G12 and they are written iteratively to a separate abaqus input file. For the time being i am considering the Poisson ratio as fixes, since it shouldn't widely change. In addition to that, I am changing the orientations by a parameter alpha between 0 and 1, which multiplies the real orientation, to obtain a new orientation vector which is written inside another separate input file. This should help the optimizer to follow a certain path during the optimiation process. Currently I am using the fminsearch function, which works perfectly for alpha = 0, however it doesn't seem to work for alpha different from 0, due to abaqus errors which arise at a certain point, due to the variables' values given by fminsearch. Is it any other matlab function which would help to solve this problem? Could your tool be helpful in this case? Thank you
Dear Artur Palasek,
The problem that you mention can occur not only for fminsearch, but also for any Matlab optimization function. It comes from certain combinations of the design variables that render the corresponding Abaqus model non-solvable, and thus the Abaqus analysis cannot complete successfully for these combinations. Therefore, you have to find some way to limit the design variable space so that it does not include combinations of design variables that lead to erroneous Abaqus models. Another common optimization function of Matlab which I use most is fmincon, but if the design space is not appropriately limited, it may give errors much like those you describe regarding fminsearch.
In any case, you can share more details about your model if you want a specialized solution to fix your problem, either here or at gpapazafeiropoulos@yahoo.gr .